Field of the Invention
The present disclosure relates to a touch type liquid crystal display device (LCD), and particularly, relates to a touch screen LCD which does not require a blocking line to block light leakage over a data line at a boundary of a touch block.
Discussion of the Related Art
Facing information society, display field of displaying electric information signals has been rapidly advanced, and accordingly, various flat display devices have been developed and used. As flat display devices, a liquid crystal display device (LCD), a plasma display panel device (PDP), an organic light emitting diode (OLED) display device and the like are used.
Among the flat display devices, LCDs are widely used because they have advantages of small size, light weight, thin profile, low power consumption, and the like.
Recently, a touch function has been added to the LCD. Particularly, to achieve thin profile, used is an in-cell touch type LCD, in which a touch screen is embedded.
FIG. 1 is a cross-sectional view illustrating an in-cell touch type LCD according to the related art.
Referring to FIG. 1, in the related art LCD, a pixel electrode 51 and a common electrode 71 are formed together in an array substrate to induce a fringe field as an electric field. This type LCD may be referred to as an FFS (fringe field switching) type or AH-IPS (advanced high performance in-plane switching) type LCD.
In the LCD, a plurality of touch blocks TB are arranged, and each touch block TB includes a group of neighboring pixel regions P arranged in row and column directions.
In the array substrate, a gate insulating layer 30 is formed on a substrate 11, and a pixel electrode 51 is formed on the gate insulating layer 30 in each pixel region P. Passivation layers 61 and 62 are formed on the pixel electrode 51, and a common electrode 71 is formed on the passivation layers 61 and 62 in each touch block TB.
The common electrode 71 includes a plurality of common patterns 72 corresponding to each pixel region P and an opening 73 between adjacent common patterns 72.
In a display period to display images, the common electrode 71 is supplied with a common voltage and functions as an opposing electrode to generate an electric field together with the pixel electrode 51. In a touch sensing period, the common electrode 71 functions as a touch electrode.
The common electrode 71 is patterned per touch block TB and is connected to a sensing line corresponding to each touch block TB, and is separated and spaced apart from a common electrode 71 of a neighboring touch block TB.
A boundary region BA between neighboring touch blocks TB is located over a data line DL. The touch electrodes 71 of the neighboring touch blocks TB are separated over the data line DL.
In this case, because of a voltage difference between the data line DL and the common electrode 71, liquid crystal around them is operated abnormally, and thus light leakage is caused at the boundary of the touch block TB.
To prevent this problem, a blocking line SHL over the data line DL at the boundary of the touch block TB is additionally required to block the light leakage, and the blocking line SHL is supplied with the same signal as the sensing line connected to the touch block TB. The blocking line SHL extends to a non-display region of the LCD and then is connected to a driving circuit as the sensing line is.
As described above, in the related art LCD, since the blocking line SHL is required in addition to the sensing line, design and manufacturing process of the LCD are complicated, and, when there is a limit on a size of an LCD, such as high-resolution model or narrow-bezel model, it is difficult to achieve such a model.
Further, as the blocking line SHL is additionally disposed over the data line DL, a load of the data line DL due to the blocking line SHL increases, and thus possibility of defect generation at the boundary of the touch block TB can increase.